Putin is a bad dude. Russia's civil society has been devastated by his actions. But he's popular in Russia precisely because he was an alternative to something far worse: The oligarchs, Yeltsin, the mob.
It's not at all clear that isolation has ever been an effective strategy against a dictator. Engagement is of course very risky, but it at least has a chance of working. Giving people alternatives, compromising with them where possible, and building hope is almost always the better strategy.